A bicycle front fork includes a fork stem extending through the head tube of a bicycle frame with a lower headset assembly connected between the lower end of the head tube and the root portion of the fork stem and an upper headset assembly connected between the upper end of the head tube and the fork stem so that the fork stem is independently rotatable relative to the head tube. The handlebar stem is securely mounted to the fork stem so that when turning the handlebar, the front wheel between the two extensions of the front fork turns while the bicycle frame is maintained. Many headset assemblies are developed to perform the features mentioned above such as European Patent 0 541 070A1 with the title of "apparatus for rotatably fitting a fork stem in a head tube of a bicycle" to Nagano, Masashi, U.S. Pat. No. 5,163,758 with the title of "journal for a head tube of a bicycle" to Chi and U.S. Pat. No. 5,095,770 having the title of "steering bearing assembly for wheeled vehicle" to Rader. The former one of the two prior patents involves a complicated structure and are used for the fork stem having threaded outer surface, and the latter one although has a simple structure and is used for the fork stem having a smooth outer surface, the position relationship between the parts of the upper headset assembly is not firmly engaged with each other so that if the bicycle is incurred a big impact, such the structural arrangement could displace.
The present invention intends to provide an upper headset assembly having bolts extending through the top cap and contacting against the pressing ring to securely position the bearing and the parts of the upper headset assembly.